Electron discharge device



Dec. 23, 1947. A. v. HAEFF 2,433,044

ELECTRON DI S CHARGE DEV I CE Filed April 24, 1942 s Sheets-Sheet 1INVENTOR Dec. 23', 1947. I v, HAEFF 2,433,044

ELECTRON DISCHARGE DEVICE Filed April 24, 1942 3 Sheets-Sheet 2 vvvvv vIINVENTOR ATTORNEY Dec. 23, 1947.

A: V. HAEFF ELECTRON DI S CHARGE DEVI CE Filed April 24, 1942 I5Sheets-Sheet 3 un a- *1 l ENTOR a2 W a C v ATTORNEY Patented Dec. 23,1947 Andrew V. Hae f', 1Witshington, D Cl, assignor to Radio Corporationof America,- a corporationof' Delaware Application Apical; 1942, serialna 440,291 1 7 Claims. (01. 2511 2 755) v My invention relates toelectron discharge de-' vices; more particularly to such devicesutilizing electron beam deflection anduseful atultra high frequencies.

In conventional-tubes utilizing beam deflection', a'be'amof electrons isdirected from the cathode 'betweena pair: of deflecting electrodestowardan apertured electrode behind which is placed an electroncollector. Alternating radio frequencyvoltagesare appliedto' thedeflecting electrodes to cause the electronbeam to 'be defiected'a-erossthe" apertured electrode, thus to control-the amount of currenttothecollector, which may be used as an output electrode. In such types oftubes the deflection 's'ensitivity' drops off as the -freduency at whichthe tube is operated is increased; that is the transco-nductance of thetube decreases. Tubes ofthis kind are also subject to the'limitation ofthe usual conventional tubes in that when operated at ultrahighfrequenciesthe presence of considerable loadingin the input circuitresults in an excessive amountof power being required to drive the tube.This decreasesthe effective power gain'of the tub when operated as-anamplifier.

Fundamental causes of high input loading are,

among'otherthings. ohmic andradiation losses due tohigh Circulatingcurrents'in electrodes and leads; Electron loading also results from thein teraction of the electron stream and the circuits connected to tubeelectrodes, and may include degenerative or regenerative effectscausedby com-' mon lead impedances.

It is an object oimy invention'to provide an electron. discharge deviceof the beam deflection type which is-particularl-ysuitable for useat'high frequencies and which has a comparatively high transconductance.

Itis another objectof my invention to providesuch a device'utilizing aninput circuit in which input-loading: is minimized, thus making moreeffective use of the driving power.

A still further object of my inventionis to provide an electrondischarge device of the beam deflection type useful at ultra highfrequencies and which employs low loss input and output electrodesystems and circuits.

A=iu-rther object of my invention is to provide such 'a" device in whichundesired coupling; due to common leads and ineffective shielding, isreduced to a minimum.

Another object of my invention is to provide an electron dischargedevice of the beam deflection type useful at ultra highfrequen'cies asan amplifier, oscillator 01" a mixer;

2" The novel features-which I- believe to be Chal?- acteristic' ofmyinventionare set forth with particularity'in the appendedclaims; butthe invention itself will-best be understoodby reference to thefollowing description taken inconnection with the accompanying drawingin which Figure 1 is; a schematic 1 longitudinal section of an electrondischarge device made accordingto my invention its associated-circuit,Figure 2 is a perspective," partly irrsection, of the electrode systemutilizedin'i thedeviceshown-in Figure 1, Figure 3 is a schematiclongitudinalsection of a modifi cation of am electron discharge devicemade according-to my invention and its associated circuit; Figure 4 isa-perspective, partly section, ofthe output tank circuit utilized in theelectron dischargedevice shown inFigure 3,'-Figures 5, 6- and-v areschematic longitudinal sections ofother modifications of my invention.

As showninFigure 1, an electron discharge device'ma'de according to myinvention comprises an envelope l0 having at, one end a cathode l I,

which may be indirectlyheated', andra pair of ac celeratingandfocusing:electrodes I 2'- l 3-, and at the other end acollector- 14' forreceiving electrons. In accordance with myinvention, 1 position' betweenthe focusing electrode andthe collectora resonant cavitytank' circuit orresonator I5 havingapai r of oppositely disposed deflecting elementsl-fi-llpositioned adjacent to and electrically connected to and supported byopposite walls ofthecavity adjacent theapertures 2Ban d;

21. Positioned between the resonant cavity and the collector is-theconducting plateflike member l8- having? anelongated aperture 19 andcentrally--positionedaconducting: rod- 20 for thuspro vid-ing a= doubleaperture. Preferably the length of the overlapping portions ofthedeflecting elementslfi and H is equal tothe distance travelled by anelectron 'du-ring a half period of the appliedcontrollin g voltage whilethe tube isin oper ation: Ithas been found that this provides maximumdeflection-sensitivity, V

A;; biasing voltage divider arrangement for the deflecting-electrodes isshown at 2 l and the output is; taken between collector Hand aperturedconducting member {8 by means of'the output transformer 24. Voltagesources for'the various electrodes are shown at. The input coupling loop22 within the resonator I5 is connectedto a coaxial transmission line23.

In operationthe biasing or polarizing voltages are appliedto electrodesl'2l3 to focus and properly direct electrons through the elongatedaperture 'of the resonantcavity tank circuit l5.

In passing through the resonant cavity the beam is subjected to atransverse alternating field between the elements I9 and I1 anddeflected across apertured element I8, the electrons being collected atI4, the double aperture in element I8 giving a desired controlvoltage-anode current characteristic.

The resonator is maintained energized by means of the input line 23 andcoupling loop 22. In one mode of excitation an electromagnetic field isset up within the cavity such that the magnetic lines of force areapproximately concentric with and coaxial with the cavity. The radiofrequency currents circulate alternately from one side of the innersurface of the cavity to the other between the apertures, causing eachof the deflecting elements I6 and H to receive a voltage thereonapproximately equal to the voltage appearing at the aperture adjacentwhich the element is connected, so that the electron stream is subjectedto a deflecting electric field.

In the modification shown in Figure 3 which utilizes a push-pull outputresonator, the input circuit is substantially the same as that shown inFigure 1. Mounted at one end of the envelope of which the resonatorsform part is an elongated cup-shaped insulation member 29 enclosingcathode 39, accelerating or modulating grid 3|, and focusing andaccelerating electrodes 32 and 33, the cup-shaped member being fused tothe collar 4| of the resonant cavity tank circuit 38. The resonantcavity tank circuit is energized by means of coupling loop 42 so that adeflecting voltage appears across electrodes 39 and 49 as explainedabove. FOllOWiIlg this resonant cavity 38 is a beam-directing andseparating electrode system housed within the insulating collar portion44 fused to the collar 43 of resonator 38 and collar 51 of resonator 48.Electrode 4'! maintained at a lower potential than the accelerating anddirecting electrodes 45 and 46 insures that the beam is directed intoone or the other of the two passageways provided in the resonant cavity48. The resonant cavity 48 is provided with reentrant tubular extensions49 and 59 separated by gap and 52 and '53 separated by gap 54, theoutput being taken by means of coupling loops 55 and 59. A collar 58supports a collector system comprising cup-shaped members 3435 havingmounted therein secondary electron suppressors 36 and 37, the envelopebeing sealed by means of the plate 59, supporting members 34 and 35.

The modulating circuit II may be utilized to modulate the stream beforeentrance of the beam into the deflecting resonator or it may be utilizedsimply as an accelerator. The biasin voltage and divider source is shownat 69 for biasing and focusing electrode elements 32 and 33. As in thefirst case the beam of electrons is deflected in passing betweenelectrodes 39 and 49 so as to pass between electrodes 41 and 46, or 45and 41, and in passing across either of the gaps 5| or 54 excites theresonant cavity 48. In the mode of oscillation utilized, each half ofthe resonator oscillates at a phase difierential of 180 with respect tothe other half so that the beam will always be decelerated in passingover gap 5| or gap 54 to maintain the resonator energized. This resultsin a push-pull output which can be extracted by means of the couplingloops 55 and 56. The manner in which the resonator 48 is caused to beenergized by inductive action is now well understood and is described inmy earlier Patent 2,237,878, issued April 8, 1941.

In the modification shown in Figure 5 I utilize a double cavity forsuccessively extracting energy from the beam passing through thiscavity. The insulating cup-shaped member 89 contains cathode GI and grid82, as well as the focusing and accelerating electrodes 83 and 84. Theelectron beam again passes through the deflectin resonant cavity tankcircuit 85 driven by coupling loop 88 and having deflecting electrodes96 and 8'! through which the beam is directed and by which the beam isdeflected. The beam is directed either between electrodes 90 and 92 or9| and 92 positioned within the collar member 89. Electrodes 98 and 9|act with the electrode 92, which is the separating electrode held at apotential lower than electrodes 99 and 9|, to direct the beam throughone or the other of the two paths through the output resonant cavitytank system 98. This system comprises a pair of cavities 94 and 95having reentrant portions 96, 91, I94 and I95 and having a separatingchamber formed by partitions I99, IOI having passageways I99 and I9Iextending therethrough. The resonant cavities are energized when thebeam passes gaps 98 and I02 and 99 and I93. Energy is extracted from theresonant cavity tank circuits 94 and 95 by means of coupling loops I01and I89 and the electrons collected by means of the cup-shaped memberI99. The modulating circuit is shown at I 91 for the grid, and thevoltage divider and voltage source I 98 is provided for acceleratingelectrodes 83 and 84. A voltage source I 99 provides the necessaryvoltages for other electrodes and the voltage divider system II9 permitsadjustment of the voltage on the beam directing electrodes 99, 9| toproperly insure that the beam will travel through the proper passageway.Cavities 9495 are separate and distinct and separated by the aperturedpartitions I99 and I9I, the transit time of the electrons being matchedto the output system such that the electrons are subjected to adecelerating field at gaps 98 and I92, and 99 and I03 in passing throughthe output system. This requires that the transit time of the electronsthrough elements I99 and IOI be equal to approximately one-half period,assuming that resonant cavity tank circuits 94 and 95 are operating outof phase. Of course this arrangement need not be used and the electrontransit time through I99 and I9I can be made more or less if a differentphase relationship is desired between the voltages induced in cavities94 and 95. The mode of oscillation for each of the cavities 94 and 95 isthe same as for cavity 48 in Figure 3.

In the modification shown in Figure 6 I employ a push-pull system in theoutput utilizing a Lecher wire arrangement and a double anode orcollector system. In this arrangement envelope III has at one endcathode II2, accelerating grid H3 and accelerating and focusingelectrodes H4 and H4, the resonant cavity II 5 being driven by couplingloop II8, which is provided with deflecting electrodes H6 and Ill.Electrons are directed into the shielded output system comprising anodeelectrodes I29 and I2I connected together by Lecher wire system I I9,the separating electrode I24 being maintained at a lower potential thanelectrodes I29 and I2I and Lecher wire system I I9. This wholearrangement is shielded by means of shielding compartment I22 and energyinductively extracted by means of coupling loop I25. The voltage sourcesfor properly biasing or polarizing are shown at I 26, I27 and I28. Sinceelectrodes I 20 and I2I operate 180 out of phase, the deflection of theelectron beam from one to the other of these two electrodes can beproperly phased to drive the output system.

In Figure 7 I show a still further modification of my inventionutilizing a doubly decelerating output circuit mounted within a cavity.Here envelope I36 has mounted at one end cathode ItI, acceleratingelectrode I32 and accelerating and focusing electrodes I33 and I34. The

resonant cavity I35 driven by coupling loop I38 is provided withdeflecting electrodes I35 and I3! for bringing about a deflection of thebeam generated by the cathode electrode system.

The output system comprises the enclosed conducting structure Ittprovided with reentrant portions I42, I i-1, I43 and lit, which with thetubular electrodes MI] and MI provide a double set of gaps I45 and I46,and I48 and I50, the separating electrode I63 extending through thebottom of the envelope and being maintained at a lower potential thanthe conducting enclosure and the elements within the enclosure. The beamin passing, for example, through the tubular member Mil to the collectorIEI is subjected to a double deceleration, giving up energy at gaps I45and I56 in a manner now well known and in accordance with the principlesset forth in my patent above referred to. Since the tubular elementsIii] and I4I extract energy from the stream 180 out of phase with eachother, they may be properly coupled by means of loop I64, which in turnis coupled to output loop I55 extending through envelope I35] and withinenclosed conducting member I39. Thus this latter arrangement provides apush-pull double decelerating device in combination with a resonantcavity circuit system for deflecting the electron beam.

In all arrangements above described the input circuit which comprisesthe resonant cavity tank circuit or resonator is a circuit of low lossboth from the standpoint of resistance and radiation losses. Loss ofdeflection sensitivity due to design of the deflecting electrodes is ata minimum and the output and input circuits because of the enclosedfields are completely shielded from each other and because of theabsence of common leads there is substantially no reaction orinteraction between the input and output systems. If desired the formsshown in the figures could be utilized as well for mixers by applying alocal oscillator voltage, for example, either to the grid electrodes SIand 8!, as shown in Figures 3 and 5, or both local oscillator and signalvoltage could be applied to coupling loops 42 and til, for example. Ineither case both voltages could be utilized for bringing aboutintermediate frequency voltages in the output system.

While I have indicated the preferred embodiments of my invention ofwhich I am now aware and have also indicated only one specificapplication for which my invention may be employed, it will be apparentthat my invention is by no means limited to the exact forms illustratedor the use indicated, but that many variations may be made in theparticular structure used and the purpose for which it is employedwithout departing from the scope of my invention as set forth in theappended claims.

What I claim as new is:

1. An electron discharge device having cathode means for supplying abeam of electrons, a cavity resonator positioned adjacent said cathodemeans and having oppositely disposed apertures in opposite walls thereofthrough which the beam path lies and deflecting electrode elementswithin said cavity resonator and separate from but electricallyconnected to opposite walls of the cavity resonator and adjacent each ofsaid apertures and having portions oppositely disposed between whichsaid beam path lies, and an output cavity resonator in the path of saidelectrons and having a pair of apertures in one wall thereof fordirecting the beam of electrons alternately through said aperturesduring operation of said electron discharge device.

2. An electron discharge device having cathode means for supplying abeam of electrons, and a cavity resonator positioned adjacent saidcathode means and having oppositely disposed apertures in opposite wallsthereof through which the beam path lies, and deflecting electrodeelements separate from but electrically connected to opposite walls ofthe cavity resonator and adjacent each of said apertures and havingportions oppositely disposed between which said beam path lies, and anoutput cavity resonator in the path of said electrons and having a pairof apertures in one wall thereof for directing the beam of electronsalternately through said apertures during operation of said electrondischarge device, and means positioned between said cavity resonatorsincluding a beam directing electrode system for assisting and directingthe beam of electrons into one or the other of the apertures of theoutput cavity resonator.

3. An electron discharge device having cathode means for supplying abeam of electrons, and a cavity resonator positioned adjacent saidcathode means and having oppositely disposed apertures in opposite wallsthereof through which the beam path lies, and deflecting electrodeelements separate from but electrically connected to opposite innerwalls of the cavity resonator and adjacent each of said apertures andhaving portions oppositely disposed between which said beam path lies,and an output cavity resonator having a pair of apertures in one wallthereof, the beam of electrons being directed alternately through saidapertures during operation of said electron discharge device, and anelectrode system positioned between said cavity resonators comprising apair of accelerating and directing electrodes oppositely disposed, andanother electrode between said oppositely disposed electrodes forseparating the electron beam during operation of the electron dischargedevice.

4. An electron discharge device having cathode means for supplying abeam of electrons, a cavity resonator positioned adjacent said cathodemeans and having oppositely disposed apertures in opposite walls thereofthrough which the beam path lies, and deflecting elements separate anddistinct from but electrically connected to opposite walls of the cavityresonator and adjacent each of said apertures and having portionsoppositely disposed between which said beam path lies, and an outputcavity resonator having a pair of apertures in one wall thereof forreceiving the beam of electrons alternately through said aperturesduring operation of said electron discharge device, said output cavityresonator having reentrant portions extending toward each other butseparated by a gap across which the electron beam is to be directed.

5. An electron discharge device having cathode means for supplying abeam of electrons, and a collector means forming an electron paththerebetween, and a cavity resonator positioned between said cathodemeans and said collector means and having oppositely disposed aperturesin opposite walls thereof through which the beam path lies, anddeflecting electrode elements electrically connected to opposite wallsof the cavity resonator and adjacent each of said apertures and havingportions oppositely disposed between which said beam path lies, and anoutput cavity resonator having a plurality of pairs of oppositelydisposed apertures in opposite walls thereof for directing the beam ofelectrons alternately through different pairs of said apertures duringoperation of said electron discharge device, said collector meansincluding a cup-shaped member, and means positioned within saidcup-shaped member for suppressing secondary electrons.

6. An electron discharge device including a cathode means for providinga beam of electrons, and collector electrode means forming an electronpath therebetween, a cavity resonator positioned adjacent said cathodemeans and having a pair of oppositely disposed apertures in oppositewalls through which the beam path lies, a pair of deflecting electrodeswithin the cavity resonator positioned adjacent said apertures andbetween which said beam path lies, collars on opposite outside walls ofsaid cavity resonator surrounding said apertures, and a cup-shapedmember enclosing said cathode means sealed to one of said collars, asecond cavity resonator provided with a collar, and an insulatingtubular member sealed between said last collar and the other collar onsaid first cavity resonator, and a beam directing and separating systemwithin said tubular member, said second cavity resonator being providedwith two pairs of oppositely disposed apertures through which theelectron beam is to be alternately directed, and means sealing saidcollector electrode means to said second cavity resonator providing anevacuated chamber for said cathode means and collector electrode means.

7. An electron discharge device having cathode means for supplying abeam of electrons, a cavity resonator positioned adjacent said cathodemeans and having oppositely disposed apertures in opposite walls thereofthrough which the path of said beam of electrons is directed, and a pairof deflecting elements within the cavity resonator positioned adjacentsaid apertures and connected to the inner walls thereof and betweenwhich the path of said beam of electrons is directed, and an outputcavity resonato system having a pair of apertures in one wall thereof,the beam of electrons being directed alternately through said aperturesduring operation of said electron discharge device.

ANDREW V. HAEFF.

REFERENEES CIZTED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,266,428 Litton Dec. 16, 19412,281,935 Hansen et a1. May 5, 1942 2,329,780 Zalesak Sept. 21, 19432,275,480 Varian et al Mar. 10, 1942 2,275,165 Varian et al. Feb. 3,1942 1,920,863 Hopkins, Jr. Aug. 1, 1933 2,103,507 Zworykin Dec. 28,1937

